Abstract: Carbon dioxide emissions have significant externalities, while formulation and implementation of climate policies from the government may contribute to the elimination for that. China has made it clear to use the “1 + N” policy system to realize its carbon peak and carbon neutralization visions, but there is still a lack of executable and restrictive policy instruments. Applying the quantitative analysis of policy content, this paper makes a two-dimensional analysis of China's carbon emission mitigation policy from main emission fields of energy, industry, construction, and transportation according to the classification of supply-oriented, environmental, and demand-oriented policy instruments. Results show that China's energy and industrial department mainly implements carbon emission reduction policies with environmental policy instruments, while policies in the building department highly rely on demand-oriented policy instruments, and policies in the transportation department pay equal attention to supply-oriented and environmental policy instruments. Specifically, the energy department mainly establishment policy conducive environment to carbon emission reduction by industrial layout, target setting, and regulatory rules, while the industrial department mainly by financial support, regulatory rules, and tax incentives. Carbon emission reduction policies in the building department highly rely on demand-based policy instruments, and the subcategories of policy instruments for technology promotion, pilot demonstrations, and major projects account for more than half of the total number of policy instruments. Science and technology investment and incentive mechanisms are the main supply-oriented policy instruments of the transportation department, and structural adjustment, financial support, and regulation rules are the main environmental policy instruments. The following problems were identified: (1) China’s carbon emission reduction policies are obviously tilted towards the energy sector, while the existing policies lack attention on the electrification level improvement of industry, building, and transportation department, and the power consumption capacity of renewable energy. (2) Unbalanced combination of policy instruments was observed in several departments. For instance, the application of regulatory approaches in the building department is insufficient. Supply-oriented policy in the transportation department is significantly more than the demand-based policy, and may no longer be able to meet the current market-driven policy demands. (3) Some frequently applied policy sub-categories, such as the technical input of supply-oriented policy instruments and the financial support of environmental policy instruments, were lack of coercive force or the policy expression is not clear, which might lead to uncertainties in implementation effects. Based on the quantitative analysis of policy content, we believe that China should optimize carbon emission reduction policy instruments from the following three aspects in achieving the carbon peaking target: (1) Appropriately increase the applied proportion of policy instruments applied in industry, building, and transportation department while maintaining the cohesion of energy supply and consumption policies. (2) Improve the accuracy and restraint of supply-oriented and environmental policy instruments to control existing emissions in the energy and industrial department. Improve the standards of regulation and access approaches in the building and transportation department in order to control the emissions incremental. (3) Accelerate the improvement of environmental and demand-oriented carbon emission reduction policy instruments in the building and transportation departments.